Flame arresting device



Nov .5,1940. G. H;JETT' 2,220,720

FLAME ARRE'STING DEVICE Filed Oct. 8, 1937 5 Sheets-Sheet 1 m imogz BY 26 ATTORNEY.

Nov.5, 1940. 2 H T' 2,220,720

FLAME ARRESTING DEVICE Filed Oct. 8, 1937 3 Sheets-Sheet 2 INVENTORi JVw7 ATTORNEY..

Nov. 5, 1940. Y G, H. JETT 2,220,720

' FLAME ARRESTING DEVICE 7 Filed Oct. is, 1957 s Sheets-Sheet s PatentedNov. 5, 1940 UNITED STATES FLAME ARRESTIN G DEVICE George H. Jett,

Application October 8,

2 Claims.

This invention relates to flame arresters and has for its particularobjects the provision of a compact, simple and highly efiective deviceof that type which is adapted to effectively prevent the hazard of fireor explosion of volatile solvents, such as petroleum vapors anddistillates, as well as coal tar distillates, etc., when the same aretransported in tankers or stored in land tanks. Other objects of myinvention are hereinafter set forth.

In the accompanying drawings in which I have illustrated a preferredembodiment of my invention Figure 1 is a vertical section of my improvedflame arrester;

Fig. 2 is a fragmentary detail section showing a cylindrical frame ofthe device immediately following the insertion of a spacing ring intothe clamping member of said frame and prior to its being locked thereinby compression of said clamping member; m

Fig. 3 is a section, similar to Fig. 2, but showing the position of theparts after the compression of said clamping member;

Fig. 4 is a plan view, on a reduced scale, of the device shown in Fig.1;

Fig. 5 is a transverse section on the line 55 of Fig. 1, on a reducedscale;

Fig. 6 is a vertical section showing a simplified form of my improvedflame arrester wherein a single cylindrical frame, only, is employed;and

Fig. 7 is a plan view, on a reduced scale and partly broken away, of thedevice shown in Fig. 6.

Referring to the drawings and construction shown therein, the referencenumeral l designates the supporting pipe for my improved arrester, thesame comprising a pipe section having top and bottom external flanges 2and 3 and in-' ternal projecting lugs 4. The bottom flange 3 of thisbase member is adapted to be bolted to a breather pipe, of similarinternal diameter, of a tank containing inflammable volatile fluids,such for example as petroleum or coal tar distillates and which tank itis desired to protect against a fire hazard or explosion.

Upper and lower cylindrical frames, comprising annular grooved clampingmembers 5 and 5, spacing rings 6 and 6, respectively mounted therein,and outer and inner wire screens a: and y are supported respectively onthe flange 2 of the pipe I and flange 2' of an intermediate shell 1,each of which flanges has its top face a, a re spectively machined toform a suitable seat therefor. The shell I is in turn supported by thetop clamping member 5 of the lower cylindrical Elizabeth, N. J.

1937, Serial No. 167,913

frame and is providedwith a depending skirt 1' that projects across. theexternal face of the outer screen, being spaced therefrom so as toafford an annular opening or vent b for the admission of air beneathsaid skirt or hood. Said shell is also provided with heat-radiating ribs8 which are disposed intermediate said skirt and the flange 2. A covermember 9 is mounted on the top of the ring 5 of the upper cylindricalframe, said cover also having a depending skirt *10 9 which extendsacross the face of the outer screen of said top frame and also is spacedtherefrom and from the lower shell 7 so as to form an annular vent oropening b. The-cover has a circular, positioning rib ll' formed on theinner face thereof which is of slightly smaller external diameter thanthe internal diameter of the grooved ring 5' of the upper cylindricalframe. The bolts l2, which are threaded into tapped lugs 4 and which areprovided with nuts l3 and locking nuts M on their upper ends, serve toretain the upper and lower cylindrical frames and the shell 1 and cover9 in their assembled relation on the base 2. The grooves I5 and 05' ofthe clamping members 5, 5f are originally formed of uniform width fromtop to "bottom thereof and the spacing rings 6, 6 have concave orbevelled faces, as indicated by the reference numerals l1 and I 1, thesebevelled faces functioning as hereinafter described to rigidly securethe screens a: and 1/ within said clamping rings.

In the construction shown in Fig. 6 and '7, wherein a single cylindricalframe is employed, the pipe member I is generally similar to theconstruction shown in Fig. 1, but the lower cylindrical frame and theintermediate shell "I are omitted and due to the abbreviated height ofthis type of flame arrester the bolts 20, which serve to secure theparts in their assembled position, are considerably shorter in length.

I am well aware that it has been proposed as. set forth in Patent No.1,672,042, to provide a flame arrester for. tanks or reservoirscontaining evaporative fluids which employed a pair of spaced,concentric screens mounted on a cylindrical frame, one of which screensWas of sufficiently fine mesh to serve as a flame arrester while theother was of a coarser mesh and served to protect the inner screen frommechanical injury as well as to prevent the collection of foreignmaterial around said inner screen. Accordingly I do not broadly claimany such construction herein, the claims being confined to a combinationwhich includes essential features other than those disclosed in saidpatent.-

In assembling my improved flame arrester, each of the cylindrical framesis first assembled as a unit by inserting the metal spacing rings 6 and6 between the inner and outer fine mesh screens at and 1/, which screensare preferably 40 mesh and formed of No. 30 B 8: S Monel metal wire. Thetwo screens with the spacing rings 6 and 6 interposed between the sameat the top and bottom thereof, are then inserted in the top and bottomclamping members and 5 whereupon the side walls of said clamping membersare compressed so as to force the same into snug engagement with theconcave channels I! or II formed on each of the vertical sides of saidspacing rings. clamping members 5 and 5 serves not only to draw thescreens taut but, due to the stiffness of the metal from which the sameare formed, the frame will be rigid and the upper and lower rings 5 and5 will be maintained or spaced at a uniform distance from each otherwhen the said frames are completed.

The cylindrical frames having been assembled, one of them is applied tothe flange 2 of the pipe I, the shell I is then positioned thereon inthe manner shown in Fig. 1, the second cylindrical frame is then appliedto the top of the flange 2' of said shell, the cover 9 is then appliedas shown in Fig. 1 to the top of said second cylindrical frame and theentire assembly is then bolted together by means of bolts I2 and nuts l3and Hi.

It is desirable that the spacing between the screens should be not lessthan A,", as thereby not only the friction drop of the vapor or gasespassing thereover is decreased, as compared with two concentricallyarranged screens in contact with each other, but also, during a ventfire on a tanker, when such an arrester'is employed, a siren-likewarning signal which will be audible to all persons on deck, will begenerated in those cases where the gases issuing through the screenshave a gasoline content, prior to ignition thereof, from 2 /2% to 3% anda sufiicient air content to support perfect combustion. This warningsignal is due to the immediate ignition of the gases upon issuancethrough the screens and. the resultant flame being consequently inimmediate contact with the outer surface of the outer screen, it willplay overthe same and cause it to become red hot. This rise intemperature of the screen greatly augments the speed of flow of thegases through the same, thus producing the siren-like signal. On theother hand, in the case of richer mixtures, containing insufiicient airto support complete combustion, the gases will not be ignited until theyhave passed to some distance beyond the screen and the resultant flame,being relatively remote from the outer surface of the screen, the latterwill not become so intensely heated as to result in the generation ofthe aforesaid warning signal.

The importance of the wedge construction as herein described formaintaining screens taut and the locking the same in their positionwithin the cylindrical frame, can best be appreciated when it isrealized that because of the high temperature which is often attainedwhen the gases escaping through the screens are ignited, it is notfeasible to employ solder to secure the screens in position. In fact,the employment of solder would be extremely hazardous. Furthermore, itis of the utmost importance to maintain the screens at all times taut soas to be spaced from each other, as otherwise the friction drop isincreased because of such contact Such compression of the sides of theupon distortion of one screen with the other. Said clamping means asherein described also serves to insure excellent heat conductivitybetween the screens, the spacing rings 6, and 6' and the grooved rings 5and 5 clamped thereto and thereby as above stated, the screens areprotected at all times from becoming so excessively hot as to melt orrupture.

It is particularly desirable that the height of the screen should notexceed about two inches from any point on the surface thereof to a heavysupporting member having a high index of heat conductivity, such forexample as the metal spacing rings 6, B and metal rings 5, 5' whichintimately engage the latter, as thereby there is no possibility of thescreens becoming so hot as to melt and rupture.

In my improved flame arrester, because of the manner in which thescreens are disposed, namely, in concentric relation with respect to theaxis, if extended, of the pipe to be vented, there is far lessrestriction or friction drop of the gases and consequently should anexplosion occur on the closed side, there is far less likelihood ofmechanical damage to the screen than in the case of multiple fiatscreens placed horizontally directly across the mouth of the vent pipe.

This application is a continuation in part of my copending applicationNo. 734,807 filed July 24, 1934, for Flame arresting device.

In the construction, as stated the screens are made preferably of Monelmetal and are consequently not subjected to deterioration by salt wateror by the corrosive gases resulting from use of the equipment with sourcrude oil or the like. Alternatively the screens can be made of othermetals combining great mechanical strength, good heat conductingqualities and resistance to corrosion by salt atmosphere or gas fumes.Such screens of Monel are quite high in chromium and nickel and low incopper, with no zinc or aluminum. The screens are strong mechanicallyand withstand explosions within the pipe I. The screens have excellentheat conductive properties. The screens have a large net effective areafor the passage of gases therethrough, which area is at least equal tothe free pipe area to which the flame arrester is connected. In theembodiment described the effective area is 1 times the area of the pipeI. The large effective area for the passage of gases is secured withoutexcessive screen dimension by mounting the screens as concentric hollowcylinders with internal spacers to keep the screens a full apart, evenafter considerable exposure to flame has caused warping or bulging ofthe screens. The device permits of relatively great ease in cleaning,and clogging of the screens with oily material or the like is minimized.

The structure described stops a flame under all conditions whenexplosion occurs on the open side of the vent. By open is meant the sideof the vent contained within a hood or enclosure having free access tothe atmosphere. The flame arrester withstands the heat generated by aprolonged vent fire with flame playing against the outside of the grid.The design and construction is such that the materials used withstandthe maximum temperatures likely to be generated in this service. Thestructure provides for free conduction of the heat from the wire screenby providing heat conducting joints between the arrester grid and thebell shaped cover. The

structure provides large surface external parts capable of absorbing,conducting away and dissipating the heat.

The flame arrester is immune from the passage of flame when ignitionoccurs in the closed pipe I. The width of the cylindrical screen ring issuch that the heat can be conducted away from all parts of the screenand dissipated into the atmosphere rapidly.

Various changes may be made within the scope of the appended claims inwhich it is desired to claim all novelty inherent in the invention asbroadly as the prior art permits.

Having thus described my invention, what I claim and desire to obtain byUnited States Letters Patent is:

l. A flame arresting device, comprising a cylindrical body formed of aplurality of superimposed sections united into a unitary assembly andwhich sections are spaced from each other to form an annular gaspassage, a plurality of spaced, concentrically arranged, cylindricalflame-arresting metallic screens spanning said gas passage, spacingmembers interposed between said screens at the respective upper andlower ends thereof and annular clamping grooved members whose lateralsurfaces inside the groove thereof are concentric with the adjacentlateral surfaces of said spacing members,

2. A flame arrester assembly, comprising a pipe end, a cylindrical frameformed of superimposed members united together and spaced from eachother to form a lateral gas passage, a

plurality of spaced, concentrically arranged, cylindrical,flame-arresting metallic screens covering said openings, annularterminal supports for the ends of each screen, said supports each havingan annular channel therein, and annular spacing members interposedbetween the adjacent ends of each pair of screens and projecting intothe channels of said supports, the adjacent surfaces of each support andits associated spacing member being respectively of convex curva- 25ture and of concave curvature.

GEORGE H. JETT.

